Belts (such as safety belts) are usually included in seating devices, such as car seats or safety seats, to assure passenger safety. In such case, buckle devices may be used for fastening or retaining the belts.
Referring to FIG. 1, a conventional buckle device (a) for fastening a belt includes a securing member (a1), a frame (a2) and a slide member (a3). The securing member (a1) is fixedly mounted to a base of a seat. The frame (a2) has a pivoting arm that is pivotally connected to the securing member (a1) to enable the frame (a2) to rotate relative to the securing member (a1), a pair of side arms that are connected to the pivoting arm, and a forearm that is connected to the side arms. The slide member (a3) is connected slidably to the side arms between the forearm and the pivoting arm. When in use, a belt may be extended through a space between the slide member (a3) and the pivoting arm from one side of the frame (a2) (e.g., a bottom side), through a space between the slide member (a3) and the forearm from another side of the frame (a2)(e.g., a top side) to surround the slide member (a3), and then away from the frame (a2). When a force is applied to the belt along its longitudinal direction, the slide member (a3) may be driven by the belt to move toward the forearm, thereby enabling the forearm and the slide member (a3) to cooperatively clamp the belt. However, when the force applied to the belt is not along the longitudinal direction thereof, the frame (a2) may be easily rotated, such that the slide member (a3) may slide relative to the frame (a2) to release the belt under inappropriate circumstances and result in safety issues.